NEET PG Medical – 2012 – Question – 44
Locking of knee joint can be caused by:
a) Osgood Schlatter
b) Loose body in knee joint
c) Tuberculosis of knee
d) a and b both
Correct Answer – D
Ans. is. D. a and b both
Locking of knee joint (i.e. joint held in flexion) is seen in meniscus tear, loose body (d/t osteochondral fracture) and fractures of tibial spine.
Mechanism of Locking
Normally the medial meniscus or at least its anterior movable portion glides slightly backwards towards the interior of joint as the knee is flexed.
If the tibia is at the same time abducted (valgus) and the medial compartment of the knee thus opened up, the mobility of the meniscus is still further increased.
Sudden medial rotation of femur on the fixed tibia forces the medial meniscus towards back of joint and causes medial ligament to become taut and it may undergo variety of transverse or oblique tear.
The inner fragment slips into the interior of the joint and when , extension is attempted and the knee begins to screw home’ the fragment is nipped between the condyles and the joint is ‘locked’ i.e. held in flexion.
